Yes, I agree that is the friends view, and we both agree they were wrong. As for the words "adds rebellion to his sin" those are Elihu's words in 34:37. Elihu is making this claim. So he believes Job has not only sinned (which he has not) but now he is also adding rebellion to it. That is what Elihu says
i don't agree.
i think it's clear that Elihu is referring to the words of Eliphaz, Bildad and Zophar in 34:35-37, which is what 34:34 says he is doing, and that's witnessed by the next paragraph too in 35, where after saying this he immediately asks, do you think this is right?
"do you think this is right" is not a question you ask about something you just stated with confidence as your own view. it's something you ask when you quote what someone else has said, particularly, something you yourself don't agree with.
Elihu doesn't accuse Job of sin, and the text explicitly tells us he is angry with those who do. what he says about Job is this:
Job 33:12-13
Look, [in] this you are not righteous. I will answer you, For God is greater than man. Why do you contend with Him? For He does not give an accounting of any of His words.
Elihu says it is not righteous for Job to contend with God over his troubles. that's it.
and God answers, proclaiming how infinitely greater than Job He is.
but does God give Job an account of why any of this has happened to him? nope.
just like Eliphaz said.
Job is humbled and repents of contending with God - exactly the thing Eliphaz said he should do.